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                    updateHostComponent
            
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                    updateHostText
            
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                    updateSuspenseComponent
            
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        <li class="chapter " data-level="1.4.7.9" data-path="../flow/begin-work/update-portal-component.html">
            
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                    updatePortalComponent
            
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                    updateForwardRef
            
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                    commit 阶段
            
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                    commitPlacement
            
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                    commitDeletion
            
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                    commitAllLifecycle
            
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                    事件对象生成
            
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                    Suspense
            
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                    挂起任务的含义
            
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                    lazy 组件
            
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                    其他API
            
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                                <h1 id="react">React</h1><blockquote><p>&#x867D;&#x7136;&#x5E73;&#x65F6;&#x6211;&#x4EEC;&#x90FD;&#x559C;&#x6B22;&#x8BF4;&#x6211;&#x4EEC;&#x7528;<code>React</code>&#x4F5C;&#x4E3A;&#x6211;&#x4EEC;&#x7684;&#x6838;&#x5FC3;&#x6846;&#x67B6;&#xFF0C;&#x4F46;&#x5176;&#x5B9E;&#x5927;&#x90E8;&#x5206;&#x4EBA;&#x90FD;&#x4E0D;&#x77E5;&#x9053;<code>React</code>&#x5230;&#x5E95;&#x662F;&#x4E2A;&#x4EC0;&#x4E48;&#x4E1C;&#x4E1C;&#x3002;&#x4E8B;&#x5B9E;&#x4E0A;&#x81EA;&#x4ECE;Facebook&#x628A;<code>React</code>&#x548C;<code>ReactDOM</code>&#x5206;&#x5305;&#x53D1;&#x5E03;&#x4E4B;&#x540E;&#xFF0C;<code>React</code>&#x5C31;&#x4E0D;&#x4EC5;&#x4EC5;&#x662F;&#x4E00;&#x5F00;&#x59CB;&#x7684;&#x524D;&#x7AEF;&#x6846;&#x67B6;&#x4E86;&#xFF0C;&#x5982;&#x679C;&#x5728;15&#x7248;&#x672C;&#x4E4B;&#x540E;&#x53BB;&#x770B;&#x4E00;&#x4E0B;<code>react</code>&#x548C;<code>react-dom</code>&#x7684;&#x6E90;&#x7801;&#x5927;&#x5C0F;&#xFF0C;&#x4F60;&#x5C31;&#x4F1A;&#x53D1;&#x73B0;&#xFF0C;<code>react</code>&#x4EC5;&#x4EC5;1000&#x591A;&#x884C;&#x4EE3;&#x7801;&#xFF0C;&#x800C;<code>react-dom</code>&#x5374;&#x5C06;&#x8FD1;2w&#x884C;&#x3002;&#x662F;&#x7684;&#x4F60;&#x6CA1;&#x770B;&#x9519;&#xFF0C;&#x800C;&#x4E14;&#x4F60;&#x5F88;&#x53EF;&#x80FD;&#x4E5F;&#x6CA1;&#x6709;&#x60F3;&#x9519;&#xFF0C;&#x5176;&#x5B9E;&#x5927;&#x90E8;&#x5206;&#x7684;&#x6846;&#x67B6;&#x903B;&#x8F91;&#x90FD;&#x5728;<code>react-dom</code>&#x5F53;&#x4E2D;&#xFF0C;&#x90A3;&#x4E48;<code>react</code>&#x5230;&#x5E95;&#x662F;&#x4E2A;&#x4EC0;&#x4E48;&#x4E1C;&#x4E1C;&#x5462;&#xFF1F;</p></blockquote><p>&#x5173;&#x4E8E;&#x7248;&#x672C;&#xFF0C;&#x672C;&#x4E66;&#x662F;&#x5728;React16+&#x7684;&#x57FA;&#x7840;&#x4E0A;&#x5199;&#x7684;&#xFF0C;React16&#x76F8;&#x8F83;&#x4E8E;&#x4E4B;&#x524D;&#x7684;&#x7248;&#x672C;&#x662F;&#x6838;&#x5FC3;&#x4E0A;&#x7684;&#x4E00;&#x6B21;&#x91CD;&#x5199;&#xFF0C;&#x867D;&#x7136;&#x4E3B;&#x8981;&#x7684;API&#x90FD;&#x6CA1;&#x6709;&#x53D8;&#x5316;&#xFF0C;&#x4F46;&#x662F;&#x589E;&#x52A0;&#x4E86;&#x5F88;&#x591A;&#x80FD;&#x529B;&#x3002;&#x5E76;&#x4E14;&#x9996;&#x6B21;&#x5F15;&#x5165;&#x4E86;<code>Fiber</code>&#x7684;&#x6982;&#x5FF5;&#xFF0C;&#x4E4B;&#x540E;&#x65B0;&#x7684;&#x529F;&#x80FD;&#x90FD;&#x662F;&#x56F4;&#x7ED5;<code>Fiber</code>&#x8FDB;&#x884C;&#x5B9E;&#x73B0;&#xFF0C;&#x6BD4;&#x5982;<code>AsyncMode</code>&#xFF0C;<code>Profiler</code>&#x7B49;&#x3002;</p><p>&#x8FD9;&#x91CC;&#x5E76;&#x4E0D;&#x4F1A;&#x8BB2;16&#x7248;&#x672C;&#x4E4B;&#x524D;&#x7684;&#x5B9E;&#x73B0;&#xFF0C;&#x4E00;&#x662F;&#x9762;&#x5411;&#x672A;&#x6765;&#xFF0C;&#x4E8C;&#x662F;&#x4E4B;&#x524D;&#x7248;&#x672C;&#x7684;&#x6E90;&#x7801;&#x6211;&#x4E5F;&#x6CA1;&#x770B;&#x8FC7;&#x3002;</p><p>&#x6211;&#x4EEC;&#x6765;&#x770B;&#x4E00;&#x4E0B;React&#x66B4;&#x9732;&#x51FA;&#x6765;&#x7684;API</p><pre><code class="lang-js"><span class="hljs-keyword">const</span> React = {
  Children: {
    map,
    forEach,
    count,
    toArray,
    only,
  },

  createRef,
  Component,
  PureComponent,

  createContext,
  forwardRef,

  Fragment: REACT_FRAGMENT_TYPE,
  StrictMode: REACT_STRICT_MODE_TYPE,
  unstable_AsyncMode: REACT_ASYNC_MODE_TYPE,
  unstable_Profiler: REACT_PROFILER_TYPE,

  createElement: __DEV__ ? createElementWithValidation : createElement,
  cloneElement: __DEV__ ? cloneElementWithValidation : cloneElement,
  createFactory: __DEV__ ? createFactoryWithValidation : createFactory,
  isValidElement: isValidElement,

  version: ReactVersion,

  __SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: ReactSharedInternals,
};</code></pre>
<p>&#x8BF7;&#x5148;&#x65E0;&#x89C6;<code>__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED</code></p><h3 id="children">Children</h3><p>&#x8FD9;&#x4E2A;&#x5BF9;&#x8C61;&#x63D0;&#x4F9B;&#x4E86;&#x4E00;&#x5806;&#x5E2E;&#x4F60;&#x5904;&#x7406;<code>props.children</code>&#x7684;&#x65B9;&#x6CD5;&#xFF0C;&#x56E0;&#x4E3A;<code>children</code>&#x662F;&#x4E00;&#x4E2A;&#x7C7B;&#x4F3C;&#x6570;&#x7EC4;&#x4F46;&#x662F;&#x4E0D;&#x662F;&#x6570;&#x7EC4;&#x7684;&#x6570;&#x636E;&#x7ED3;&#x6784;&#xFF0C;&#x5982;&#x679C;&#x4F60;&#x8981;&#x5BF9;&#x5176;&#x8FDB;&#x884C;&#x5904;&#x7406;&#x53EF;&#x4EE5;&#x7528;<code>React.Children</code>&#x5916;&#x6302;&#x7684;&#x65B9;&#x6CD5;&#x3002;</p><h3 id="createref">createRef</h3><p>&#x65B0;&#x7684;<code>ref</code>&#x7528;&#x6CD5;&#xFF0C;React&#x5373;&#x5C06;&#x629B;&#x5F03;<code>&lt;div ref=&quot;myDiv&quot; /&gt;</code>&#x8FD9;&#x79CD;<code>string ref</code>&#x7684;&#x7528;&#x6CD5;&#xFF0C;&#x5C06;&#x6765;&#x4F60;&#x53EA;&#x80FD;&#x4F7F;&#x7528;&#x4E24;&#x79CD;&#x65B9;&#x5F0F;&#x6765;&#x4F7F;&#x7528;<code>ref</code></p><pre><code class="lang-js"><span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">App</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">React</span>.<span class="hljs-title">Component</span></span>{

  <span class="hljs-keyword">constructor</span>() {
    <span class="hljs-keyword">this</span>.ref = React.createRef()
  }

  render() {
    <span class="hljs-keyword">return</span> &lt;div ref={this.ref} /&gt;
    // or
    return &lt;div ref={(node) =&gt; this.funRef = node} /&gt;
  }

}</code></pre>
<h3 id="component--purecomponent">Component &amp; PureComponent</h3><p>&#x8FD9;&#x4E24;&#x4E2A;&#x7C7B;&#x57FA;&#x672C;&#x76F8;&#x540C;&#xFF0C;&#x552F;&#x4E00;&#x7684;&#x533A;&#x522B;&#x662F;<code>PureComponent</code>&#x7684;&#x539F;&#x578B;&#x4E0A;&#x591A;&#x4E86;&#x4E00;&#x4E2A;&#x6807;&#x8BC6;</p><pre><code class="lang-js"><span class="hljs-keyword">if</span> (ctor.prototype &amp;&amp; ctor.prototype.isPureReactComponent) {
  <span class="hljs-keyword">return</span> (
    !shallowEqual(oldProps, newProps) || !shallowEqual(oldState, newState)
  );
}</code></pre>
<p>&#x8FD9;&#x662F;&#x68C0;&#x67E5;&#x7EC4;&#x4EF6;&#x662F;&#x5426;&#x9700;&#x8981;&#x66F4;&#x65B0;&#x7684;&#x4E00;&#x4E2A;&#x5224;&#x65AD;&#xFF0C;<code>ctor</code>&#x5C31;&#x662F;&#x4F60;&#x58F0;&#x660E;&#x7684;&#x7EE7;&#x627F;&#x81EA;<code>Component or PureComponent</code>&#x7684;&#x7C7B;&#xFF0C;&#x4ED6;&#x4F1A;&#x5224;&#x65AD;&#x4F60;&#x662F;&#x5426;&#x7EE7;&#x627F;&#x81EA;<code>PureComponent</code>&#xFF0C;&#x5982;&#x679C;&#x662F;&#x7684;&#x8BDD;&#x5C31;<code>shallowEqual</code>&#x6BD4;&#x8F83;<code>state</code>&#x548C;<code>props</code>&#x3002;</p><p>&#x987A;&#x4FBF;&#x8BF4;&#x4E00;&#x4E0B;&#xFF1A;<strong>React&#x4E2D;&#x5BF9;&#x6BD4;&#x4E00;&#x4E2A;ClassComponent&#x662F;&#x5426;&#x9700;&#x8981;&#x66F4;&#x65B0;&#xFF0C;&#x53EA;&#x6709;&#x4E24;&#x4E2A;&#x5730;&#x65B9;&#x3002;&#x4E00;&#x662F;&#x770B;&#x6709;&#x6CA1;&#x6709;<code>shouldComponentUpdate</code>&#x65B9;&#x6CD5;&#xFF0C;&#x4E8C;&#x5C31;&#x662F;&#x8FD9;&#x91CC;&#x7684;<code>PureComponent</code>&#x5224;&#x65AD;</strong></p><h3 id="createcontext">createContext</h3><p><code>createContext</code>&#x662F;&#x5B98;&#x65B9;&#x5B9A;&#x7A3F;&#x7684;<code>context</code>&#x65B9;&#x6848;&#xFF0C;&#x5728;&#x8FD9;&#x4E4B;&#x524D;&#x6211;&#x4EEC;&#x4E00;&#x76F4;&#x5728;&#x7528;&#x7684;&#x8001;&#x7684;<code>context API</code>&#x90FD;&#x662F;React&#x4E0D;&#x63A8;&#x8350;&#x7684;API&#xFF0C;&#x73B0;&#x5728;&#x65B0;&#x7684;API&#x91CA;&#x51FA;&#xFF0C;&#x5B98;&#x65B9;&#x4E5F;&#x5DF2;&#x7ECF;&#x786E;&#x5B9A;&#x5728;17&#x5927;&#x7248;&#x672C;&#x4F1A;&#x628A;&#x8001;<code>API</code>&#x53BB;&#x9664;&#x3002;</p><p>&#x65B0;API&#x7684;&#x4F7F;&#x7528;&#x65B9;&#x6CD5;&#xFF1A;</p><pre><code class="lang-js"><span class="hljs-keyword">const</span> { Provider, Consumer } = React.createContext(<span class="hljs-string">&apos;defaultValue&apos;</span>)

<span class="hljs-keyword">const</span> ProviderComp = (props) =&gt; (
  <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">Provider</span> <span class="hljs-attr">value</span>=<span class="hljs-string">{&apos;realValue&apos;}</span>&gt;</span>
    {props.children}
  <span class="hljs-tag">&lt;/<span class="hljs-name">Provider</span>&gt;</span></span>
)

<span class="hljs-keyword">const</span> ConsumerComp = () =&gt; (
  <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">Consumer</span>&gt;</span>
    {(value) =&gt; <span class="hljs-tag">&lt;<span class="hljs-name">p</span>&gt;</span>{value}<span class="hljs-tag">&lt;/<span class="hljs-name">p</span>&gt;</span>}
  <span class="hljs-tag">&lt;/<span class="hljs-name">Consumber</span>&gt;</span></span>
)</code></pre>
<p>&#x540E;&#x9762;&#x8BB2;<code>context</code>&#x4F1A;&#x4E13;&#x95E8;&#x6BD4;&#x8F83;&#x65B0;&#x8001;&#x7684;API&#x7684;&#x5DEE;&#x5F02;&#xFF0C;&#x63D0;&#x524D;&#x8BF4;&#x4E00;&#x53E5;&#xFF0C;&#x8001;API&#x7684;&#x6027;&#x80FD;&#x4E0D;&#x662F;&#x4E00;&#x822C;&#x7684;&#x5DEE;</p><h3 id="forwardref">forwardRef</h3><p><code>forwardRef</code>&#x662F;&#x7528;&#x6765;&#x89E3;&#x51B3;HOC&#x7EC4;&#x4EF6;&#x4F20;&#x9012;<code>ref</code>&#x7684;&#x95EE;&#x9898;&#x7684;&#xFF0C;&#x6240;&#x8C13;HOC&#x5C31;&#x662F;<code>Higher Order Component</code>&#xFF0C;&#x6BD4;&#x5982;&#x4F7F;&#x7528;<code>redux</code>&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x6211;&#x4EEC;&#x7528;<code>connect</code>&#x6765;&#x7ED9;&#x7EC4;&#x4EF6;&#x7ED1;&#x5B9A;&#x9700;&#x8981;&#x7684;state&#xFF0C;&#x8FD9;&#x5176;&#x4E2D;&#x5176;&#x5B9E;&#x5C31;&#x662F;&#x7ED9;&#x6211;&#x4EEC;&#x7684;&#x7EC4;&#x4EF6;&#x5728;&#x5916;&#x90E8;&#x5305;&#x4E86;&#x4E00;&#x5C42;&#x7EC4;&#x4EF6;&#xFF0C;&#x7136;&#x540E;&#x901A;&#x8FC7;<code>...props</code>&#x7684;&#x65B9;&#x5F0F;&#x628A;&#x5916;&#x90E8;&#x7684;<code>props</code>&#x4F20;&#x5165;&#x5230;&#x5B9E;&#x9645;&#x7EC4;&#x4EF6;&#x3002;<code>forwardRef</code>&#x7684;&#x4F7F;&#x7528;&#x65B9;&#x6CD5;&#x5982;&#x4E0B;&#xFF1A;</p><pre><code class="lang-js"><span class="hljs-keyword">const</span> TargetComponent = React.forwardRef((props, ref) =&gt; (
  <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">TargetComponent</span> <span class="hljs-attr">ref</span>=<span class="hljs-string">{ref}</span> /&gt;</span>
))</span></code></pre>
<p>&#x8FD9;&#x4E5F;&#x662F;&#x4E3A;&#x4EC0;&#x4E48;&#x8981;&#x63D0;&#x4F9B;<code>createRef</code>&#x4F5C;&#x4E3A;&#x65B0;&#x7684;<code>ref</code>&#x4F7F;&#x7528;&#x65B9;&#x6CD5;&#x7684;&#x539F;&#x56E0;&#xFF0C;&#x5982;&#x679C;&#x7528;<code>string ref</code>&#x5C31;&#x6CA1;&#x6CD5;&#x5F53;&#x4F5C;&#x53C2;&#x6570;&#x4F20;&#x9012;&#x4E86;&#x3002;</p><p>&#x8FD9;&#x91CC;&#x53EA;&#x662F;&#x7B80;&#x5355;&#x8BF4;&#x4E00;&#x4E0B;&#x4F7F;&#x7528;&#x65B9;&#x6CD5;&#xFF0C;&#x540E;&#x9762;&#x8BB2;<code>ref</code>&#x7684;&#x65F6;&#x5019;&#x4F1A;&#x8BE6;&#x7EC6;&#x5206;&#x6790;&#x3002;</p><h3 id="&#x7C7B;&#x578B;">&#x7C7B;&#x578B;</h3><pre><code class="lang-js">Fragment: REACT_FRAGMENT_TYPE,
StrictMode: REACT_STRICT_MODE_TYPE,
unstable_AsyncMode: REACT_ASYNC_MODE_TYPE,
unstable_Profiler: REACT_PROFILER_TYPE,</code></pre>
<p>&#x8FD9;&#x56DB;&#x4E2A;&#x90FD;&#x662F;React&#x63D0;&#x4F9B;&#x7684;<em>&#x7EC4;&#x4EF6;</em>&#xFF0C;&#x4F46;&#x4ED6;&#x4EEC;&#x5462;&#x5176;&#x5B9E;&#x90FD;&#x53EA;&#x662F;&#x5360;&#x4F4D;&#x7B26;&#xFF0C;&#x90FD;&#x662F;&#x4E00;&#x4E2A;<code>Symbol</code>&#xFF0C;&#x5728;React&#x5B9E;&#x9645;&#x68C0;&#x6D4B;&#x5230;&#x4ED6;&#x4EEC;&#x7684;&#x65F6;&#x5019;&#x4F1A;&#x505A;&#x4E00;&#x4E9B;&#x7279;&#x6B8A;&#x7684;&#x5904;&#x7406;&#xFF0C;&#x6BD4;&#x5982;<code>StrictMode</code>&#x548C;<code>AsyncMode</code>&#x4F1A;&#x8BA9;&#x4ED6;&#x4EEC;&#x7684;&#x5B50;&#x8282;&#x70B9;&#x5BF9;&#x5E94;&#x7684;Fiber&#x7684;<code>mode</code>&#x90FD;&#x53D8;&#x6210;&#x548C;&#x4ED6;&#x4EEC;&#x4E00;&#x6837;&#x7684;<code>mode</code></p><h3 id="createelement--cloneelement--createfactory--isvalidelement">createElement &amp; cloneElement &amp; createFactory &amp; isValidElement</h3><p><code>createElement</code>&#x53EF;&#x8C13;&#x662F;React&#x4E2D;&#x6700;&#x91CD;&#x8981;&#x7684;API&#x4E86;&#xFF0C;&#x4ED6;&#x662F;&#x7528;&#x6765;&#x521B;&#x5EFA;<code>ReactElement</code>&#x7684;&#xFF0C;&#x4F46;&#x662F;&#x5F88;&#x591A;&#x540C;&#x5B66;&#x5374;&#x4ECE;&#x6CA1;&#x89C1;&#x8FC7;&#x4E5F;&#x6CA1;&#x7528;&#x8FC7;&#xFF0C;&#x8FD9;&#x662F;&#x4E3A;&#x5565;&#x5462;&#xFF1F;&#x56E0;&#x4E3A;&#x4F60;&#x7528;&#x4E86;JSX&#xFF0C;JSX&#x5E76;&#x4E0D;&#x662F;&#x6807;&#x51C6;&#x7684;js&#xFF0C;&#x6240;&#x4EE5;&#x8981;&#x7ECF;&#x8FC7;&#x7F16;&#x8BD1;&#x624D;&#x80FD;&#x53D8;&#x6210;&#x53EF;&#x8FD0;&#x884C;&#x7684;js&#xFF0C;&#x800C;&#x7F16;&#x8BD1;&#x4E4B;&#x540E;&#xFF0C;<code>createElement</code>&#x5C31;&#x51FA;&#x73B0;&#x4E86;&#xFF1A;</p><pre><code class="lang-js">// jsx
&lt;div id=&quot;app&quot;&gt;content&lt;/div&gt;

// js
React.createElement(&apos;div&apos;, { id: &apos;app&apos; }, &apos;content&apos;)</code></pre>
<p><code>cloneElement</code>&#x5C31;&#x5F88;&#x660E;&#x663E;&#x4E86;&#xFF0C;&#x662F;&#x7528;&#x6765;&#x514B;&#x9686;&#x4E00;&#x4E2A;<code>ReactElement</code>&#x7684;</p><p><code>createFactory</code>&#x662F;&#x7528;&#x6765;&#x521B;&#x5EFA;&#x4E13;&#x95E8;&#x7528;&#x6765;&#x521B;&#x5EFA;&#x67D0;&#x4E00;&#x7C7B;<code>ReactElement</code>&#x7684;&#x5DE5;&#x5382;&#x7684;&#xFF0C;</p><pre><code class="lang-js"><span class="hljs-keyword">export</span> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">createFactory</span>(<span class="hljs-params">type</span>) </span>{
  <span class="hljs-keyword">const</span> factory = createElement.bind(<span class="hljs-literal">null</span>, type);
  factory.type = type;
  <span class="hljs-keyword">return</span> factory;
}</code></pre>
<p>&#x4ED6;&#x5176;&#x5B9E;&#x5C31;&#x662F;&#x7ED1;&#x5B9A;&#x4E86;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x7684;<code>createElement</code>&#xFF0C;&#x4E00;&#x822C;&#x6211;&#x4EEC;&#x7528;JSX&#x8FDB;&#x884C;&#x7F16;&#x7A0B;&#x7684;&#x65F6;&#x5019;&#x4E0D;&#x4F1A;&#x7528;&#x5230;&#x8FD9;&#x4E2A;API</p><p><code>isValidElement</code>&#x987E;&#x540D;&#x601D;&#x4E49;&#x5C31;&#x662F;&#x7528;&#x6765;&#x9A8C;&#x8BC1;&#x662F;&#x5426;&#x662F;&#x4E00;&#x4E2A;<code>ReactElement</code>&#x7684;&#xFF0C;&#x57FA;&#x672C;&#x4E5F;&#x7528;&#x4E0D;&#x592A;&#x5230;</p>
                                
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